linux-kernel - Re: [PATCH] f2fs: let fill_super handle roll-forward errors

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Message-ID: <30b91d0c-63b2-0082-0132-3f188c1a4602@huawei.com>
Date:   Tue, 15 Aug 2017 19:45:03 +0800
From:   Chao Yu <yuchao0@...wei.com>
To:     Jaegeuk Kim <jaegeuk@...nel.org>
CC:     <linux-kernel@...r.kernel.org>, <linux-fsdevel@...r.kernel.org>,
        <linux-f2fs-devel@...ts.sourceforge.net>, <stable@...r.kernel.org>
Subject: Re: [PATCH] f2fs: let fill_super handle roll-forward errors

On 2017/8/15 11:22, Jaegeuk Kim wrote:
> On 08/15, Chao Yu wrote:
>> Hi Jaegeuk,
>>
>> On 2017/8/11 8:42, Jaegeuk Kim wrote:
>>> If we set CP_ERROR_FLAG in roll-forward error, f2fs is no longer to proceed
>>> any IOs due to f2fs_cp_error(). But, for example, if some stale data is involved
>>> on roll-forward process, we're able to get -ENOENT, getting fs stuck.
>>> If we get any error, let fill_super set SBI_NEED_FSCK and try to recover back
>>> to stable point.
>>
>> Before that, we have cleaned up all node/meta page cache, so we will get back to
>> last checkpoint status, means losing fsynced datas for ever.
>>
>> Would it be better to just leave message reminding user to mount with
>> disable_roll_forward or run fsck offline.
> 
> We can't rely on user for this, since fsck cannot recover this, resulting in

If fsck has no ability to recover this, it could tag superblock in somewhere,
then kernel could skip recovery. Comparing to fail recovery directly, it give
user another chance to rescuer his datas.

Thanks,

> infinite mount failure. The only way is to disable roll-forward recovery, which
> is same as returning error here.
> 
> Thanks,
> 
>>
>> Thanks,
>>
>>>
>>> Cc: <stable@...r.kernel.org>
>>> Signed-off-by: Jaegeuk Kim <jaegeuk@...nel.org>
>>> ---
>>>  fs/f2fs/recovery.c | 2 --
>>>  1 file changed, 2 deletions(-)
>>>
>>> diff --git a/fs/f2fs/recovery.c b/fs/f2fs/recovery.c
>>> index a3d02613934a..f707d810c87d 100644
>>> --- a/fs/f2fs/recovery.c
>>> +++ b/fs/f2fs/recovery.c
>>> @@ -649,8 +649,6 @@ int recover_fsync_data(struct f2fs_sb_info *sbi, bool check_only)
>>>  	}
>>>  
>>>  	clear_sbi_flag(sbi, SBI_POR_DOING);
>>> -	if (err)
>>> -		set_ckpt_flags(sbi, CP_ERROR_FLAG);
>>>  	mutex_unlock(&sbi->cp_mutex);
>>>  
>>>  	/* let's drop all the directory inodes for clean checkpoint */
>>>
> 
> .
>